echo '1a2a3a4a5' | awk 'BEGIN{RS="a"}{print $1}'

echo '1ab2bc3cd4de5' | awk 'BEGIN{RS="[a-z]+"}{print $1,RS,RT}'

awk 'BEGIN{RS=""}{print $0}' 1.txt

seq 5|awk 'BEGIN{ORS="|"}{print $0}'

echo '1ab2bc3cd4de5' | awk 'BEGIN{FS="[a-z]+"}{print $1,$2,$5}'

echo ' 1 2' | awk 'BEGIN{FS=" "}{print $1}'

echo ' 1 2' | awk 'BEGIN{FS="[ \t\n]+"}{print $1}'

echo '1 2 3 4 5' | awk -v OFS="|" '{NF+=0;print $0}'

awk 'FNR==1{if(NR>1) print "";print "==> "FILENAME" <=="}1;FNR==10{nextfile}' [abc].txt

awk '{print NR,$0 > "d.txt"}' a.txt

awk 'BEGIN{getline;print FILENAME,ARGV[ARGIND],$0}' a.txt
